Some students find it difficult to read notes in sheet music. For example, the student practices playing particular sounds on a musical instrument, but may not be able to tell whether they provide a correct sound in comparison with a note on the sheet music. Some students simply play a sound based on a remembered melody or composed series of notes, but not necessarily based on reading the note. Music teachers can inform the student when they provide an incorrect sound, but the teachers' knowledge is based on years of training and practice. The student is somewhat abandoned if the teacher is unavailable and the student wants to practice reading sheet music. Also, the student needs to find different music to practice or the student will play the notes from memory instead of reading the note.